1. Field of the Invention
The present invention relates to the field of flat panel displaying, and in particular to an AMOLED (Active Matrix Organic Light Emitting Diode) driving circuit and driving method.
2. The Related Arts
A flat display device has various advantages, such as thin device body, low power consumption, and being free of radiation, and is thus of wide applications. The flat display devices that are currently available include liquid crystal displays (LCDs) and organic electroluminescence devices (OELDs), which are also referred to as organic light emitting diodes (OLEDs).
The organic electroluminescence devices, which show the characteristics of self-illumination, high brightness, wide view angle, high contrast, flexibility, and low energy consumption, attract wide attention for serving as the next-generation display measures and gradually substitute the conventional liquid crystal displays for wide applications in various fields including mobile phone screens, computer monitors, and full-color television. The organic electroluminescence devices are different from the conventional liquid crystal displays in that they need no backlight and they use extremely thin coating layers of organic materials directly formed on the glass substrates so that when electrical currents flow therethrough, the organic material coating layers emit light.
The currently available organic light emitting diodes are classified according to the driving methods used and include a passive-matrix organic light emitting diode (PMOLED) and an active-matrix organic light emitting diodes (AMOLED). The process of manufacturing technology and material of the flat panel displays brings the AMOLED to the mainstream of future flat panel displays.
Referring to FIG. 1, which is a diagram showing a driving circuit of a conventional AMOLED panel, the driving circuit comprises two thin-film transistors 100, 200 and a storage capacitor 300. After being charged, the storage capacitor 300 applies a control voltage to a gate terminal of the second thin-film transistor 200 to set the second thin-film transistor 200 in a saturation zone in order to supply an electrical current to and light up the AMOLED panel. A driving circuit adopting such a structure, although simple in structure, may affect the threshold voltage Vth of the second thin-film transistor 200 because the second thin-film transistor 200 has been long affected by electrons, and consequently, the electrical current of the AMOLED panel will be affected, leading to influence of uniformity of the AMOLED panel and thus deterioration of the displaying quality of the AMOLED panel.